AC Drive for a Portable Duct Cleaner

A portable duct cleaner is designed to perform source removal duct cleaning inside various types of structures including homes, hospitals and commercial high-rises. Compared to clumsy van or truck-mounted units, this portable system offers exceptional flexibility needed to access and clean air handling systems on the first floor or the fifty-first floor.

The duct cleaner is a vacuum that is attached directly to the air handling system within the building. The vacuum produces a powerful airflow in the duct that pulls dirt and debris into the filtration system. As the vacuum operates, the filter begins to clog with debris which increases the AC line current. The application required that maximum air flow be maintained during this process without nuisance tripping of the circuit breaker.

An AC drive is needed to monitor and adjust the motor speed as the filter begins to clog. The drive must be simple to operate, capable of working with both 15 AMP and 20 AMP circuits, and be GFCI compatible. The drive was required to be mounted inside the duct cleaning unit and able to withstand vibration.

KB Solution:

KB engineers selected model KBAC-24D with custom software for this application. The drive was configured to operate with GFCI’s and was designed to be jumper selectable for both 15 AMP and 20 AMP circuits.

The KBAC uses a custom software algorithm to automatically maximize the vacuum performance without tripping the circuit breaker. The software monitors the AC line current and adjusts the motor speed to keep the current below the circuit breaker rating. This allows the duct cleaner to maintain maximum airflow as the filter begins to clog. An on board indicator alerts the operator when to change the filter.

In addition to the custom software, the standard NEMA 4X enclosure was modified to allow the drive to be installed within the allotted space in the equipment. In order for the drive to withstand the shock and vibration during use, the application required that a silicon compound be used to secure several of the components.